Multicomponent thermoset structures

ABSTRACT

Composite structures are described that include (a) a first polymer structure (e.g., a film or solid component) made of EPDM adhered to (b) a second polymer structure (film or solid component) that is made of a blend of dynamically vulcanized EPDM dispersed in a matrix of a thermoplastic polyolefin polymer. Either the first polymer structure, or both the first and second polymer structures are blended with an effective amount of a semicrystalline random adhesive copolymer.

This applications claims the benefit of Provisional Application No.60/257,721, filed Dec. 22, 2000.

Join Research Agreement: On 01 Jan. 1991, Exxon Corp. (now Exxon MobilCorp.) and Advanced Elastomer Systems, L.P., executed agreements forjoint research and technology sharing in the field of thermoplasticelastomer products, the field of this invention.

FIELD OF INVENTION

The present invention relates to polymer composite structures havingimproved adhesion properties. For example, a two component polymercomposite structure is disclosed, in which one of the polymer structuresis made of EPDM blended with an effective amount of a semicrystallinerandom adhesive copolymer, and the other polymer structure is made of ablend of dynamically vulcanized EPDM dispersed in a matrix of athermoplastic polyolefin polymer. This second polymer structure may alsobe blended with a semicrystalline random adhesive copolymer.

As discussed below, certain aspects of the invention are directed tomulti-layer films. Other aspects of this invention are directed topolymeric composite structures with separate polymeric componentsadhered to one another, where the components are not films. For example,certain composite structures form parts of motor vehicles, e.g.,automobiles. These structures include elastomeric sealing structures(sometimes referred to as “sealing systems”) in cars, such as extrudedprofiles and moldings. More specifically, such sealing structures mayinclude glass run channels, door seals and belt line seals. Certainstructures provide insulation to air, water, or noise and/or they may beconfigured to provide for the sliding of glass against the sealingsurface. Such composite structures also may simply be part of theaesthetic design features of a car. Many components used in compositestructures for automobiles are formed from polymer such as curedelastomers, e.g., EPDM, alone or blended with other polymers. Thecomponents in these composites are often adhered to one another. Acontinuing need exists for improved adhesion between two EPDM componentsor between an EPDM component and a component with a differentcomposition, particularly at elevated temperatures, e.g., 60° C. orhigher.

SUMMARY OF INVENTION

In one specific embodiment of the invention, a composite structure isdisclosed that includes (a) a first polymer structure (e.g., a film orsolid component) made of EPDM blended with an effective amount of asemicrystalline random adhesive copolymer adhered to (b) a secondpolymer structure (film or solid component) that is made of a blend ofdynamically vulcanized EPDM dispersed in a matrix of a thermoplasticpolyolefin polymer.

The first polymer structure contains semicrystalline random adhesivecopolymer in the amount of from 5 to 50 phr (parts per hundred parts ofrubber), i.e., based on the amount of EPDM or other elastomericmaterial. Preferably, the semicrystalline random adhesive copolymer ispresent in the amount of from 15 to 30 phr. More preferably, thesemicrystalline random adhesive copolymer is present in the amount of 25phr.

In another embodiment of the invention, the second polymer structurealso contains semicrystalline random adhesive copolymer in an amounteffective to further improve adhesion between the components of thecomposite structure. Preferably the semicrystalline random adhesivecopolymer is present in the amount of from about 5 to about 50 weightpercent, based on the weight of the thermoplastic polyolefin polymerpresent in the second polymer structure.

DETAILED DESCRIPTION OF INVENTION

Various specific embodiments, versions and examples of the inventionwill now be described, including preferred embodiments and definitionsthat are adopted herein for purposes of understanding the claimedinvention. It is understood, however, that the scope of the “invention”will refer to the appended claims, including their equivalents, andelements or limitations that are equivalent to those that are recited.All references to the “invention” below are intended to distinguishclaimed compositions and methods from compositions and methods notconsidered to be part of this invention. It is understood, therefore,that any reference to the “invention” may refer to one or more, but notnecessarily all, of the inventions defined by the claims. References tospecific “embodiments” are intended to correspond to claims coveringthose embodiments, but not necessarily to claims that cover more thanthose embodiments.

The term “polymer structure” is defined herein to include anysubstantially flat structure that may be adhered to one another, such asfilms, which include sheets, layers and the like, and in some cases thestructure may be partially melted, e.g., during adhesion. The term“polymer structure” also includes any “non-flat” structure, such as amolded part that is used in automobiles, discussed above, in which casethe structure may have a curved or rounded surface. However, the term“polymer structure” is defined as not including any particulate matter,such as pellets.

One of the polymer structures of the composite structures describedherein are preferably “thermoplastic” materials, which term as usedherein refers to a plastic that can be repeatedly softened by heatingand hardened by cooling. Also, one or both of the polymer structures ofthe composite structures described herein may also include thermoset orthermosetting plastics. The terms “thermoset” and “thermosettingplastic” as used herein are defined as referring to any plastic thathardens permanently after being heated once. Preferably, the EPDMstructures are crosslinked. The term “crosslinked” as used herein refersto any material that has been subjected to a procedure that causescrosslinking in the polymer chain, e.g., to create branching. A materialcan be crosslinked by curing or vulcanizing. Thus, for example, acrosslinked elastomeric material may include a vulcanized EPDM.

A specific embodiment of the invention relates to a composite structurethat includes a first polymer structure, for example a film or solidcomponent (which may be either dense or foamed) made of EPDM blendedwith an effective amount of a semicrystalline random adhesive copolymeradhered to a second polymer structure (film or solid component) that ismade of a blend of dynamically vulcanized EPDM dispersed in a matrix ofa thermoplastic polyolefin polymer. An example of the latter blend isone sold under the trademark Santoprene, and is available from AdvancedElastomer Systems, L.P., Akron, Ohio.

In this specific embodiment, the first polymer structure containssemicrystalline random adhesive copolymer in the amount of from 5 to 50phr (parts per hundred parts of rubber), i.e., based on the amount ofEPDM or other elastomeric material. Preferably, the semicrystallinerandom adhesive copolymer is present in the amount of from 15 to 30 phr.More preferably, the semicrystalline random adhesive copolymer ispresent in the amount of 25 phr.

In a specific embodiment, a composite structure has a first polymerstructure that is made from an elastomeric material, preferably an EPDM,and additionally includes one or more of the ingredients specified inTable 1 below, or their chemical equivalent, and a second polymerstructure that is made from a thermoplastic elastomer (TPE) blend asdisclosed elsewhere herein, e.g., a blend of dynamically vulcanized EPDMor other elastomeric material or TPE dispersed in a matrix of athermoplastic polyolefin polymer, e.g., an isotactic polypropylene or anethylene-propylene copolymer.

In a specific embodiment, a composite structure having the propertiesidentified in Table 8 is provided. For example, a specific embodiment ofthis invention includes a composite film structure having substantiallyimproved adhesion properties. Also, for example, a specific embodimentincludes a two-component composite structure in which one of the polymercomponents includes EPDM blended with a semicrystalline random copolymerin an amount of 5 to 50 phr, preferably 15 to 30 phr, more preferably 25phr. Preferably, that composite structure has energy at break ofadhesion that is 50% greater than a two-component composite structurethat includes a polymer component with EPDM but not any semicrystallinerandom copolymer. Also, preferably, the adhesion failure mode in thestructure that includes the semicrystalline random copolymer is shiftedfrom adhesive to cohesive, demonstrating thermoplastic stock failure atroom temperature and preferably also at elevated temperature (70° C.).

Thermoplastic Elastomer Component

The composite structure of this invention includes what is sometimesreferred to as a “second polymer structure,” i.e., the polymer structurethat includes a dynamically vulcanized EPDM or other elastomer and athermoplastic polyolefin polymer. A number of blends can be used to formthe second polymer structure, which are described below, or areidentified in the patents that are incorporated by reference. Athermoplastic elastomer (TPE) can be generically defined as arubber-like material that, unlike conventional rubbers, can be processedand recycled like thermoplastic materials (ASTM D 1566). When the TPEcontains a vulcanized rubber, it may also be referred to as athermoplastic vulcanizate (TPV), defined as a TPE with a chemicallycross-linked rubbery phase, produced by dynamic vulcanization (ASTM D1566). The term “dynamically vulcanized” refers in general to a materialthat has been subjected to “dynamic vulcanization,” a term that isherein intended to include a vulcanization process in which athermoplastic polyolefin resin and a vulcanizable elastomer arevulcanized under conditions of high shear. As a result, the vulcanizableelastomer is simultaneously crosslinked and dispersed as fine particlesof a “micro gel” within the engineering resin.

As used herein, the terms TPE and TPV refer to a blend of thermoplasticpolyolefin resin and at least partially vulcanized rubber. Suchmaterials have the characteristic of elasticity, i.e. they are capableof recovering from large deformations quickly and forcibly. One measureof this rubbery behavior is that the material will retract to less than1.5 times its original length within one minute, after being stretchedat room temperature to twice its original length and held for one minutebefore release (ASTM D 1566). Another measure is found in ASTM D 412,for the determination of tensile set. the materials are alsocharacterized by high elastic recovery, which refers to the proportionof recovery after deformation and may be quantified as percent recoveryafter compression. A perfectly elastic material has a recovery of 100%while a perfectly plastic material has no elastic recovery. Yet anothermeasure is found in ASTM D 395, for the determination of compressionset.

Procedures for dynamically vulcanizing materials, and the materials thatcan be included in the second polymer structure herein are disclosed inU.S. Pat. Nos. 4,311,628 and 5,672,660, incorporated herein by referencefor purposes of United States patent practice. In addition to or insteadof EPDM, the second polymer structure can also include other TPEs.Examples of TPEs are disclosed in U.S. Pat No. 6,147,180, incorporatedherein by reference for purposes of United States patent practice.

A further specific embodiment includes a two-component compositestructure as described above in which both polymer components areblended with a semicrystalline random copolymer. That is, the secondpolymer structure also includes a semicrystalline random copolymer in anamount of from about 5 to about 50 weight percent, preferably from about10 to about 20 weight percent, of semicrystalline random copolymer,based on the weight of the thermoplastic polyolefin polymer present inthe second polymer structure. In this embodiment the energy at break ofadhesion is further improved over the embodiment wherein thesemicrystalline random copolymer is blended only with the EPDMcomponent.

Semicrystalline Random Copolymer Component

The composite structures described herein include a “semicrystallinerandom copolymer” (SRC). The term “random copolymer” as used herein isdefined as a copolymer in which the distribution of the monomer residuesis consistent with the random statistical polymerization of themonomers, and includes copolymers made from monomers in a singlereactor, but does not include copolymers made from monomers in seriesreactors, which are defined herein to be “block copolymers.” The randomcopolymer discussed herein is preferably “semicrystalline,” meaning thatin general it has a relatively low crystallinity, as will be discussedmore specifically below. This semicrystalline random copolymerpreferably includes 70–88 mole % propylene units and alpha olefin unitshaving 2 carbon atoms (ethylene units) or from 4 to 10 carbon atoms,e.g., butene units or octene units. Thus, in a specific embodiment, apreferred semicrystalline random copolymer is a polypropylene polymer,specifically a propylene-ethylene copolymer, in which a substantialnumber of the copolymer units, e.g., 70–88 mole % of them, are propyleneunits. That semicrystalline random copolymer is thus distinguishablefrom copolymers made of propylene and ethylene units that have fewerthan 70 mole % propylene units, including conventional polyethylenepolymers having some amount of propylene. It has been discovered thatsuperior adhesive properties can be obtained using one or more of thesemicrystalline random copolymers described herein.

The semicrystalline random copolymer used in specific embodiments ofthis invention preferably has a crystallinity of from 2% to 65% of thecrystallinity of isotactic polypropylene. The term “crystalline” as usedherein broadly characterizes those polymers that possess a high degreeof both inter and intra molecular order, and which preferably melthigher than 110° C., more preferably higher than 115° C., and mostpreferably above 130° C. A polymer possessing a high inter and intramolecular order is said to have a “high” level of crystallinity, while apolymer possessing a low inter and intra molecular order is said to havea “low” level of crystallinity. Crystallinity of a polymer can beexpressed quantitatively, e.g., in terms of percent crystallinity,usually with respect to some reference or benchmark crystallinity. Asused herein, crystallinity is measured with respect to isotacticpolypropylene homopolymer. Preferably, heat of fusion is used todetermine crystallinity. Thus, for example, assuming the heat of fusionfor a highly crystalline polypropylene homopolymer is 190 J/g, asemicrystalline random copolymer having a heat of fusion of 95 J/g willhave a crystallinity of 50%. The term “crystallizable” as used hereinrefers to those polymers or sequences that are mainly amorphous in theundeformed state, but upon stretching or annealing, become crystalline.Thus, in certain specific embodiments, the semicrystalline randomcopolymer can be crystallizable.

The random semicrystalline copolymer preferably comprises a copolymer ofpropylene and at least one comonomer selected from the group consistingof ethylene and at least one C₄ to C₂₀ alpha-olefin, preferably havingan average propylene content of from at least about 70 mol % and morepreferably from at least about 73 mol %, and most preferably from atleast about 85 mol %. Further, the propylene copolymer has a weightaverage molecular weight (Mw) preferably from about 15,000 to about200,000 Daltons; more preferably between about 50,000 and about 150,000Daltons; and most preferably between about 65,000 and about 100,000Daltons. The semi-crystalline propylene copolymer preferably has a meltindex (MI) as measured by ASTM D 1238(B) of from about 3000 dg/min toabout 7 dg/min, more preferably from about 20 dg/min to about 900dg/min, and most preferably from about 78 to about 630 dg/min.Additionally, the semi-crystalline propylene copolymer can have a meltindex of from about 10 dg/min to about 2500 dg/min, or from about 15dg/min to about 2000 dg/min. The propylene sequences in the propylenecopolymer may be either isotactic propylene sequences or syndiotacticpropylene sequences, preferably isotactic sequences. The crystallinityin the propylene copolymer is to be derived from either the isotactic orsyndiotactic propylene sequences.

The semicrystalline polymer (SRC) can be a thermoplastic copolymer,preferably random, of ethylene and propylene having a melting point byDifferential Scanning Calorimetry (DSC) analysis (ASTM E-794–95) of fromabout 25° C. to about 120° C., preferably in the range of from about 30°C. to about 110° C., more preferably in the range of from about 65° C.to about 100° C. The semi-crystalline polymer preferably has a weightaverage molecular weight/number average molecular weight ratio (Mw/Mn)of approximately 2. A preferred semi crystalline polymer used in thepresent invention is described in detail as the “First PolymerComponent” in co-pending U.S. application Ser. No. 60/133,966, filed May13, 1999, which is incorporated by reference herein for the purpose ofUnited States patent practice. The semi-crystalline polymer preferablyhas a heat of fusion from about 30 J/g to about 80 J/g as determined byDSC, more preferably from about 40 J/g to about 70 J/g as determined byDSC, and most preferably from about 50 J/g to about 65 J/g as determinedby DSC.

A preferred procedure used in the present application for DifferentialScanning Calorimetry (DSC) is described as follows. Preferably, about 6mg to about 10 mg of a sheet of the preferred polymer pressed atapproximately 200° C. to 230° C. is removed with a punch die and isannealed at room temperature for 48 hours. At the end of this period,the sample is placed in a Differential Scanning Calorimeter (PerkinElmer 7 Series Thermal Analysis System) and cooled to about −50° C. to−70° C. The sample is heated at about 10° C./min to attain a finaltemperature of about 180° C. to about 200° C. The thermal output isrecorded as the area under the melting peak of the sample which istypically at a maximum peak at about 30° C. to about 175° C. and occursbetween the temperatures of about 0° C. and about 200° C. The thermaloutput is measured in Joules as a measure of the heat of fusion. Themelting point is recorded as the temperature of the greatest heatabsorption within the range of melting temperature of the sample.

A SRC of the present invention preferably comprises a randomcrystallizable copolymer having a narrow compositional distribution. Theterm “crystallizable,” as used herein for SRC, describes those polymersor sequences which are mainly amorphous in the undeformed state, but cancrystallize upon stretching, annealing or in the presence of anucleating agent, such as a crystalline polymer or a crystalline segmentwithin the polymer. Crystallization is measured by DSC, as describedherein. While not meant to be limited thereby, it is believed that thenarrow composition distribution of the first polymer component isimportant. The intermolecular composition distribution of the polymer isdetermined by thermal fractionation in a solvent. A typical solvent is asaturated hydrocarbon such as hexane or heptane. This thermalfractionation procedure is described in previously mentioned U.S. Ser.No. 60/133,966. Typically, approximately 75 weight % and more preferably85 weight % of the polymer is isolated as a one or two adjacent, solublefraction with the balance of the polymer in immediately preceding orsucceeding fractions. Each of these fractions has a composition (mol %ethylene content) with a difference of no greater than 27 mol %(relative) and more preferably 14 mol % (relative) of the average mol %ethylene content of the whole first polymer component. The first polymercomponent is narrow in compositional distribution if it meets thefractionation test outlined above.

In semi-crystalline polymers, the length and distribution ofstereo-regular propylene sequences is consistent with the substantiallyrandom statistical crystallizable co-polymerization. It is well knownthat sequence length and distribution are related to theco-polymerization reactivity ratios. By substantially random, we meancopolymer for which the product of the reactivity ratios is preferably 2or less, more preferably 1.5 or less, and most preferably 1.2 or less.

In stereo-block structures, the average length of PP sequences isgreater than that in substantially random copolymers with a similarcomposition. Prior art polymers with stereo-block structure have adistribution of PP sequences consistent with these blocky structuresrather than a substantially random statistical distribution. To producea crystallizable copolymer with the required randomness and narrowcomposition distribution, it is desirable to use (1) a single sitedcatalyst and (2) a well-mixed, continuous flow stirred tankpolymerization reactor which allows only a single polymerizationenvironment for substantially all of the polymer chains of the firstpolymer component.

The SRC comprises preferably isotactically crystallizable alpha-olefinsequences, e.g., preferably propylene sequences (NMR). The crystallinityof the first polymer component is, preferably, according to oneembodiment, from 1% to 65% of isotactic polypropylene, preferablybetween 3% to 30%, as measured by the heat of fusion of annealed samplesof the polymer. The SRC preferably has a poly dispersity index (PDI) orMw/Mn between 1.5 to 40, more preferably between about 1.8 to 5 and mostpreferably between 1.8 to 3. Preferably, the SCP has a Mooney viscosityof ML (1+4)@125° C. less than 40, more preferably less than 20 and mostpreferably less than 10. It is preferred that the SRC has a melt index(MI) at 190° C. of less than about 1500 dg/min, more preferably lessthan about 900 dg/min, and most preferably less than 650 dg/min.Further, the semi-crystalline propylene copolymer can also have a meltindex of from about 10 dg/min to about 2500 dg/min, or from about 15dg/min to about 2000 dg/min, or even more broadly from about 7 dg/min toabout 3000 dg/min.

The low levels of crystallinity in certain specific embodiments of theSCP can be obtained by incorporating from about 0.5 to 50 mol %alpha-olefin, preferably from about 0.9 to about 35 mol % alpha-olefin;more preferably, it comprises from about 1.3 to about 37 mol %alpha-olefin, and; most preferably between about 1.3 to about 15 mol %alpha-olefin. Alpha olefins are defined herein to comprise one or moremembers of the group consisting of ethylene and C₄–C₂₀ alpha-olefin. Atalpha-olefin compositions lower than the above lower limits for thecomposition of the SCP, the blends of the SCP are thermoplastic. Atalpha-olefin compositions within the stated desired ranges, the blendsexhibit superior tensile strength. At alpha-olefin compositions higherthan the above higher limits for the SOP, the blends have poor tensilestrength It is believed, while not meant to be limited thereby, the SCPneeds to have the optimum amount of isotactic polypropylenecrystallinity to crystallize for the beneficial effects of the presentinvention. As discussed above, the most preferred co-monomer isethylene.

Rubber Component

The term “rubber” for the purposes of this application is considered toencompass all elastomeric polymers and plastics, such as but not limitedto ethylene—alpha-olefin—diene monomer terpolymer, particularly EPDM;ethylene propylene rubber (EPR); butyl rubber, halobutyl rubber,styrene-isoprene-styrene (SIS); styrene-butadiene copolymers (SBC);polyisoprene rubber; polyisobutylene rubber (PIB);styrene-butadiene-styrene (SBS); styrene-butadiene rubber (SBR);polybutadiene rubber (BR); blends of said elastomeric polymers, as wellas blends of these rubbers with thermoplastics. The preferred rubbercomponent is a polymer derived from ethylene, one or more alpha-olefins,and one or more non-conjugated diene monomers. The preferred ethylenecontent is from about 35 to about 85 weight percent, based on the totalweight of the ethylene—alpha-olefin—diene monomer terpolymer, preferablyfrom about 40 to about 80 weight percent, and more preferably from about45 to about 75 weight percent.

The diene monomer can be one or more non-conjugated dienes containing 30carbon atoms or less, more preferably 20 carbon atoms or less. Thepreferred non-conjugated dienes include, but are not limited to one ormore of 5-ethylidene-2-norbornene (ENB); 1,4-hexadiene; 1,6-octadiene;5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; vinylnorbornene;dicyclopentadiene; and combinations thereof. The preferrednon-conjugated diene content is from about 1 to about 15 weight percent,based on the total weight of the ethylene—alpha-olefin—diene monomerterpolymer, and preferably from about 2 to about 11 weight percent.

Alpha-olefin will make up the remainder of theethylene—alpha-olefin—diene monomer terpolymer, with percentages addingup to 100 weight percent. The preferred alpha-olefins include, but arenot limited to C₃, C₄, C₆, C₈, and higher molecular weightalpha-olefins. More preferably, the alpha-olefin is propylene.

Ethylene—alpha-olefin—diene monomer terpolymers can be prepared using aconventional polymerization process, including traditional Ziegler-Nattacatalysts, as well as metallocene catalysts. Synthesis ofethylene—alpha-olefin—diene monomer terpolymers is well known in theart. Reference may be had to G. ver Strate, Encyclopedia of PolymerScience and Engineering, vol. 6, pp. 522–564 (2nd Ed., 1986).

In one embodiment, the rubber component is Vistalon™ 9500 available fromExxonMobil Chemical Company, Baytown, Tex. Vistalon™ 9500 is a polymerof ethylene-propylene-ethylidene norbornene having following typicalproperties:

Mooney Viscosity, ML 1 + 4, 125° C. 72 Ethylene content, weight %: 60ENB, weight % 11

-   -   Carbon black used in the reinforcement of rubber, generally        produced from the combustion of a gas and/or a hydrocarbon feed        and having a particle size from 20 nm to 100 nm for the regular        furnace or channel black or from 150 to 350 nm for the thermal        black. Level in the compound may range from 10 to 300 parts per        100 parts of elastomeric polymer (phr).    -   Processing oil, preferably paraffinic, is added to adjust both        the viscosity of the compound for good processing and its        hardness in the range of 50 to 85 Shore A. Level in the compound        may vary from 0 to 200 parts per hundred of elastomeric        polymer(phr).    -   Zinc oxide and stearic acid are added to activate the        accelerators and attain a good crosslink density. Typical        quantities are between 0 to 20 phr of Zinc oxide and 0 to 5 phr        of stearic acid.    -   Vulcanizing agents are used to cause the chemical reaction        resulting in crosslinking the elastomer molecular chains.        Typical are sulfur (0 to 10 phr), sulfur donor like thiuram        disulfides (tetramethyl thiuram disulfide) and thiomorpholines        (dithio dimorpholine) in the range of 0 to 10 phr).    -   Accelerators are used to reduce the vulcanization time by        increasing the speed of the crosslinking reaction. They are        typically thiazoles (2-mercaptobenzo thiazole or mercaptobenzo        thiazol disulfide), guanidines (diphenyl guanidine),        dithiocarbamates (zinc dimethyldithio carbamate, zinc        diethyldithio carbamate, zinc dibutyldithio carbamate), and        others well known by the one skilled in the art of rubber        compounding. All can be used in the range of 0 to 5 phr.

Beside sulfur vulcanization systems, peroxides can also be used ascurative. Vulcanization is described in Chapter 7 of Science andTechnology of Rubber, Academic Press Inc., 1978.

Whether sulfur or peroxide cured, the first polymer structure made ofEPDM described herein is substantially fully cured, but is in no waypartially cured. By fully cured we intend that the cured parts arethermoset, that is the cured part can not be replasticized, nor meltreprocessable.

Use of the terms parts per hundred parts rubber (phr) and the term partsper hundred elastomeric polymer, are considered equivalent for purposesof this application. Use of the term “compound” for purposes of thisapplication includes the EPDM polymer and one or more of the abovedescribed ingredients.

A rubber compounder or fabricator for automotive body parts willplasticize or masticate the elastomer while adding materials such asreinforcing materials, diluting fillers, vulcanizing agents,accelerators, and other additives which would be well known to those ofordinary skill in the art, to produce an elastomer compound for use inautomotive sealing. Generally, such plasticization, mastication, and/orcompounding, or both, takes place in a rolkl mill or an internalkneader, such as a Banbury mixer or the like. After compounding, thematerials are then fed to a device which can meter the compound (oftenan extruder) and force (screw of an extruder, piston of a press) thecompounded elastomer into molding cavities or dies for shaping andcuring. Curing can take place in heated mold cavity or in heattransferring devices continuously like hot air oven, possibly coupledwith microwave oven or bath containing a heated liquid salt medium.

The term “melting point” for a material as used herein is defined as thehighest peak among principal and secondary melting peaks as determinedby DSC, discussed above. Techniques for determining the molecular weight(Mn and Mw) and molecular weight distribution (MWD) are found in U.S.Pat. No. 4,540,753 and the references cited therein, incorporated hereinby reference for the purposes of United States patent practice, as wellas in Macromolecues 1988, vol. 21, p. 3360.

The “composition distribution” of copolymers can be measured accordingto the following procedure. About 30 g of the copolymer is cut intosmall cubes about ⅛ inch per side. These cubes are introduced into athick walled glass bottle closed with screw cap along with 50 mg ofIrganox 1076, an antioxidant commercially available from Ciba-GeigyCorporation. Then, 425 ml of hexane (a principle mixture of normal andiso isomers) is added to the contents of the bottle and the sealedbottle is maintained at about 23° C. for about 24 hours. At the end ofthis period, the solution is decanted and the residue is treated withadditional hexane for an additional 24 hours. At the end of this period,the two hexane solutions are combined and evaporated to yield a residueof the polymer soluble at 23° C. To the residue is added sufficienthexane to bring the volume to 425 ml and the bottle is maintained atabout 31° C. for 24 hours in a covered circulating water bath. Thesoluble polymer is decanted and the additional amount of hexane is addedfor another 24 hours at about 31° C. prior to decanting. In this manner,fractions of the copolymer component soluble at 40° C., 48° C., 55° C.,and 62° C. are obtained at temperature increases of approximately 8° C.between stages. Further, increases in temperature to 95° C. can beaccommodated, if heptane, instead of hexane, is used as the solvent forall temperatures about 60° C. The soluble polymers are dried, weighedand analyzed for composition, as for example by weight percent ethylenecontent, by an infrared spectrophotometer techniques described below.Soluble fractions obtained in the adjacent temperature increases are theadjacent fractions in the specification above. A polymer is said to havea “narrow compositional distribution” herein when at least 75 weightpercent of the polymer is isolated in two adjacent soluble fractions,each fraction having a composition difference of no greater than 20% ofthe average weight percent monomer content of the average first polymercomponent.

Certain specific embodiments can include a copolymer with a specifiedethylene “composition.” The ethylene composition of a polymer can bemeasured as follows. A thin homogeneous film is pressed at a temperatureof about 150° C. or greater, then mounted on a Perkin Elmer PE 1760infrared spectrophotometer. A full spectrum of the sample from 600 cm⁻¹to 400 cm⁻¹ is recorded and the monomer weight percent of ethylene canbe calculated according to the following equation: Ethylene wt%=82.585−111.987X+30.045 X², wherein X is the ratio of the peak heightat 1155 cm⁻¹ and peak height at either 722 cm⁻¹ or 732 cm⁻¹, whicheveris higher. The concentrations of other monomers in the polymer can alsobe measured using this method.

Applications

This invention includes certain extruded elastomeric polymer profilesgenerally for use as a vehicle sealing system, especially such sealingsystems known as glass run channel, door seal or belt line seal, the useof such sealing systems in vehicles and the vehicles containing suchsystems. Also contemplated is the fabrication of the glass run channel,door seal or belt line seal which may include coloring, low frictioncoating, thermoplastic veneer or thermoplastic overmolding. Theresulting sealing systems have combinations of properties rendering themsuperior and unique to profiles previously available. The elastomericpolymer profiles disclosed herein are particularly well suited for usein producing certain classes of vehicle sealing systems, glass runchannel, door seal or belt line seal and vehicles using the profiles incombination with thermoplastic elastomers. Vehicles contemplatedinclude, but are not limited to passenger autos, trucks of all sizes,farm vehicles, trains, and the like.

In an automobile, there are different types of sealing with differentfunctions, therefore constructed with different structure. For examplethe most common are door seal, glass run channel and belt line seal:

1. Door seal, where three different rubber compounds may be used. Amicrocellular profile is in contact with the car body frame, providingby compression, adequate sealing against water, air and aerodynamicnoise. A metal carrier compound, generally rigidified by a flexiblestamped metal co-extruded with the rubber, holds the sponge portion andis further gripped on the car body. Soft rubber lips inside the metalcarrier provide a tight link between the rubber components and themetallic body frame of the car. Up to now, door seals have generallybeen manufactured by using EPDM type rubber generally without any othermaterial addition.

2. Glass run channel is another profile generally composed of one typeof rubber extruded in such form that the glass is guided during therewinding operation and then insure good insulation when the glass isclosed. Movement in the channel is generally facilitated by a flockdeposit inside the rubber channel. This flock is adhered to the rubberwith a curable cement, generally chloroprene based.

3. inner or outer belt line seal is a rubber profile composed generallyof two coextruded parts: one flexible portion against the glass andmodified as described above to facilitate the motion of the glass, andone stiff portion rigidified generally with a metal, steel or aluminumcoextruded with the rubber compound.

Such elastomeric profiles can also be used in other applications thanautomotive, like railway cars, building and construction.

EXAMPLES

Characterization of EPDM

TABLE 1 Parameter Units Test EPDM Structural Com- positions* MooneyViscosity ML 1 + 4, 125° C., MU ASTMD 1646 Ethylene Weight % ASTMD 3900Ethylidene Norbornene Weight % ASTMD 6047 *ethylene, alpha-olefin, dienemonomer elastomeric polymerCharacterization of EPDM Compound

TABLE 2 Compound Properties Units Test Mooney Viscosity ML 1 + 4, ASTM D100° C., MU 1646 Mooney Scorch time Ts_(2, 5 Or 10), 125° C., ASTM Dminutes 1646 Oscillating Disk Rheometer (ODR) ASTM D @ 180° C., ±3° arc2084 ML dN.m MH dN.m Ts2 minute T₉₀ minute Cure rate dN.m minutePhysical Properties, press cured 10 minutes @ 180° C. Hardness Shore AISO 100% Modulus Mpa 7619–1986 Tensile Strength Mpa ISO 37–1977Elongation at Break % type 2 ISO 37–1977 type 2 ISO 37–1977 type 2Compression Set, press cured 8 min. @ 180° C. 22 hrs/70° C./25%deflection % ISO 815–1972(E Substrate Adhesion on thermo- Exxon testplastic elastomers (peeling (see below) at 100 mm/min) Force at breakMpa Elongation at break % Energy at break mJ

The polymer structure made of EPDM is compounded in a laboratoryinternal mixer tangential type Farrel 1.6 liter capacity; Masterbacheswere mixed in a first pass and then finalized with addition of curativesin a second pass.

Laboratory testing of adhesion of rubber to substrate are made withmolded samples.

-   -   Thermoplastic elastomer is molded onto a fully cured thermoset        elastomeric EPDM pad. This EPDM pad is inserted in a special        mold designed to simulate the material flow like in mold for end        cap or corner parts. This mold has a dimension of 60×60×3 mm.        Injection conditions are described in table 3.

TABLE 3 Injection press temperature profile 200–230 −260 −260° C. Moldtemperature 40° C. Injection speed 150 mm/sec. Injection Pressure 35 barPost injection pressure 50% of initial pressure Post injection time 10seconds Cooling time 30 seconds

-   -   Adhesion test is carried out with following conditions: a series        of S 2 dumbbells is die cut perpendicular to the injected        material, so that the dumbbell is composed of half of the        thermoplastic elastomer and by half of the elastomeric material.        The adhesion force is measured by clamping the dumbbell in an        Instron extensiometer and pulled at a speed of 100 mm/minute.

Example 1

This example describes preparation of a specific composite structurethat includes one polymer structure (film) made of EPDM blended with aneffective amount of a semicrystalline random adhesive copolymer adheredto another polymer structure (film) made of a blend of dynamicallyvulcanized EPDM dispersed in a matrix of a thermoplastic polyolefinpolymer. The latter blend is sold under the trademark Santoprene, and isavailable from Advanced Elastomer Systems, L.P.

In this example, two EPDM polymer films were made, differing in that thesecond EPDM polymer film (Compound II) included a semicrystalline randomcopolymer adhesive having a Mooney visocisty (ML 1+4, 125° C.) of 12, amelting point of 75° C., a propylene content of 84.9 mol % and an MFR of2.8 g/10 min (190° C., 2.16 kg, while the first EPDM polymer film(Compound I) had none of the copolymer. Table 4 shows the ingredientsused to make each of the two EPDM films. Tables 5 and 6 show theproperties of the polymer films made of EPDM. Films made of Compounds Iand II were then adhered to films prepared from a grade of Santoprenethermoplastic elastomer formulated to have enhanced adhesion toengineering resins, as described in published International patentapplication WO 00/37553, incorporated herein by reference for thepurpose of United States patent practice. The adhesion properties of theresulting composite film structures are reported in Table 8. Thecomposite film structure that included the semicrystalline randomcopolymer showed substantially improved adhesion properties. It wasobserved, for example, that the energy at break of adhesion wasincreased by 50% over the composite film that did not include thesemicrystalline random copolymer, and actually shifted the adhesionfailure mode from adhesive to cohesive (thermoplastic stock failure)both at room temperature and at elevated temperature (70° C.).

TABLE 4 Compound Batch, in phr (part per hundred of rubber) Compound ICompound II EPDM Vistalon ™ 9500 100 100 SRC with high C3 fraction 0 25Spheron ™ 5000 130 130 Flexon ™ 815 80 80 Zinc Oxide 5 5 Stearic Acid 11 Calcium Oxide 80% 5 5 Sulfur 1.5 1.5 MBT (75%) 0.8 0.8 DPTT (75%) 1.31.3 ZDBDC (80%) 1.3 1.3 DPG 0.5 0.5 Total Weight 326.4 351.4Rheology of the compounds and cure characteristics are described intable 5.

TABLE 5 Mooney Viscosity 57 43 ML (1 + 4), 100° C., M.U Mooney Scorch,125° C. 4.5 5.5 Ts 5, minutes ODR ±3° arc, 180° C. ML, dN.m 9 6 MH, dN.m68 49 MH-ML, dN.m 59 43 Ts₂, min 0.5 0.6 T₉₀, min 2.0 2.5 Cure ratedN.m/min 99 58Physical characteristics of the thermoset elastomeric compound aremeasured after curing in a press for 5 minutes at 180° C. Results aredescribed in table 6.

TABLE 6 Physical Properties, Press cured 5 minutes at 180° C. Compound ICompound II Hardness, shore A 71 71 100% Modulus, MPa 4.7 4.2 TensileStrength, MPa 11 9.6 Elongation at break, % 255 265 Compression Set 2353 22 hrs/70° C./25% def, %Thermoplastic elastomer available from Advanced Elastomer System. (blendof dynamically cured EPDM dispersed in a matrix of thermoplasticpolyolefin polymers) is ready to use as available from the vendor,without compounding, has physical properties described in table 7

TABLE 7 Tensile strength, MPa 3.9 Elongation @ break, % 680 Energy @break, mJ 2650Adhesion results are described in the table 8:

TABLE 8 Thermoset reference Modified thermoset Elastomeric rubbercompound compound Thermoplastic elastomer Santoprene TPE Santoprene TPETest at 23° C. Adhesion Force, MPa 3.1 3.5 Elongation @ break, % 520 670Energy @ break, mJ 1570 2350 Test at 70° C. Force at break, MPa 1.2 1.5Elongation @ break, % 345 490 Energy @ break, mJ 413 730A cohesive failure (tear in the thermoplastic elastomer portion) isobtained when an elastomeric material modified with the elastomercontaining large fraction of propylene is used. This is achieved at bothroom temperature and 70° C.

Example 2

Composite structures are prepared from a first polymer of EPDM, adheredto a second polymer of a blend of dynamically vulcanized EPDM dispersedin a matrix of a thermoplastic polyolefin polymer. The second polymerwas a general purpose grade of thermoplastic elastomer having noenhanced adhesive properties (Santoprene thermoplastic vulcanizate fromAdvanced Elastomer Systems, L.P.).

In this example both the first and second polymer includedsemicrystalline random copolymer (SRC) described in Example 1. Theamount of semicrystalline random copolymer in the first polymer (EPDM)was maintained at a constant 25 phr. The amount of semicrystallinerandom copolymer in the second polymer was varied by replacing a portionof the thermoplastic polyolefin polymer (polypropylene) with thesemicrystalline random copolymer. The amount of semicrystalline randomcopolymer in the second polymer was varied over the range from 0 to 35weight percent of the weight of the thermoplastic polyolefin polymer inthe second polymer.

The composition and properties of the composite structures are set forthin Table 9. The structures which included the semicrystalline randomcopolymer in both the first and second polymer components showedsubstantially improved adhesion properties at ambient temperature overthe composite which included the semicrystalline random copolymer inonly the EPDM component.

TABLE 9 SRC¹ in SRC in EPDM TPE Modulus² Elongation² UTS² Energy³ Sample(phr) (wt. %) (100%) at break (%) (MPa) (mJ) 3 25 0 2.8 104 2.8 294 4 2510 2.5 170 3 503 5 25 15 2.8 148 3.2 474 6 25 17.5 2.6 481 6.3 3030 7 2525 2.1 401 4.3 1730 8 25 30 1.8 352 3.5 1216 9 25 35 1.8 457 4.8 2194¹semicrystalline random copolymer ²ASTM D412-92 at 23° C. ³UTS ×Elongation at break

1. An elastomeric sealing structure comprising: (a) a first polymerstructure made of an thermoset EPDM material blended with from 5 to 50phr of a semicrystalline random copolymer adhered to (b) a secondpolymer structure made of a blend of a dynamically vulcanizedelastomeric material dispersed in a matrix of a thermoplastic polyolefinpolymer, wherein said sealing structure is one of extruded profiles ormoldings.
 2. The composite structure of claim 1 in which thesemicrystalline random copolymer is present in the amount of from 15 to30 phr, based on the EPDM material.
 3. The composite structure of claim1 in which the semicrystalline random copolymer has a crystallinity offrom 2% to 65% of the crystallinity of isotactic polypropylene.
 4. Thecomposite structure of claim 1 in which the semicrystalline randomcopolymer includes 70–88 mole % propylene units and alpha olefin unitshaving 2 carbon atoms or from 4 to 10 carbon atoms.
 5. The compositestructure of claim 1 in which the second polymer structure is made froma blend of dynamically vulcanized EPDM dispersed in a matrix of apropylene polymer.
 6. The composite structure of claim 5 in whichcomposite structure has energy at break of adhesion at least 50% greaterthan the energy at break of adhesion of a composite structure in whichthe elastomeric material of the first and second polymer structuresinclude EPDM but do not include semicrystalline random copolymer.
 7. Thecomposite structure of claim 1 in which the first polymer structure andthe second polymer structure are both non-film structures.
 8. Thesealing structure of claim 1 wherein said structure is for an automobileand is selected from the group consisting of glass run channels, doorseals, belt line seals, insulation, roof seals, trunk seals and hoodseals.
 9. The composite structure of claim 1 in which the second polymerstructure (b) also contains from 5 to 50 weight percent of asemicrystalline random copolymer, based on the weight of thethermoplastic polyolefin polymer in (b).
 10. The composite structure ofclaim 9 in which the semicrystalline random copolymer is present in anamount of from 10 to 20 weight percent.
 11. The composite structure ofclaim 9 in which the semicrystalline random copolymer has acrystallinity of from 2% to 65% of the crystallinity of isotacticpolypropylene.
 12. The composite structure of claim 9 in which thesemicrystalline random copolymer includes 70–88 mole % propylene unitsand alpha olefin units having 2 carbon atoms or from 4 to 10 carbonatoms.
 13. The composite structure of claim 9 in which the secondpolymer structure is made from a blend of dynamically vulcanized EPDMdispersed in a matrix of a propylene polymer.
 14. The compositestructure of claim 9 in which the elastomeric materials in the first andsecond polymer structures comprise EPDM, and the composite structure hasenergy at break of adhesion at least 50% greater than the energy atbreak of adhesion of a composite structure in which the elastomericmaterial of the first and second polymer structures include EPDM but inwhich the second polymer structure does not include semicrystallinerandom copolymer.